kermit911
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Joined: Mon Feb 24, 2014 9:21 pm

Thinking about getting a Raspberry Pi

Mon Feb 24, 2014 9:27 pm

Hello everyone, I am new to the Pi world and I have watch many YouTube videos. I do have a quick question, the main purpose for me considering to buy the Pi is I need something that will make a small strip of LED's flash once every 30 seconds. Is that possible with the Pi? If you need more information please let me know.

Thank you
Kermit

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joan
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Location: UK

Re: Thinking about getting a Raspberry Pi

Mon Feb 24, 2014 11:05 pm

Have a look through http://www.themagpi.com/home/

ame
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Location: New Zealand

Re: Thinking about getting a Raspberry Pi

Mon Feb 24, 2014 11:53 pm

If that's all you need to do, then I'd recommend the "555". If you think you might want to do more then the Pi will do this and more. Or an Arduino. Take your pic.

kermit911
Posts: 5
Joined: Mon Feb 24, 2014 9:21 pm

Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 12:19 am

Thank you, the 555 I'm not sure how to put together. I have never done anything like this before. Is it simple to program the Pi to do what I need?

Thanks
Dave

ame
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Location: New Zealand

Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 12:37 am

If you just want to flash some LEDs you would be better off with a simple, dedicated circuit. However, having a Pi means you can do that and learn more about electronics, programming and Linux.

You will need:
A Pi
An SD card with the Pi operating system
A USB power supply
A USB keyboard
An HDMI monitor or a TV with composite video input

You will also need some bits and bobs for the LED control circuit, which you will connect to the GPIO pins on the Pi.

Do you have the LED strip already? What are the power requirements for the LED strip (voltage and current)?

kermit911
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Joined: Mon Feb 24, 2014 9:21 pm

Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 12:46 am

Sweet, the LED's are 12V 300mA LED's

Here is a Link:
http://www.radioshack.com/product/index ... lsrc=aw.ds

Thanks
Kermit

ame
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Location: New Zealand

Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 2:03 am

Ok, well you'll need some electronic components to switch the LEDs on and off under control of the Pi.

The GPIO signals can not handle 12V or 300mA so you will need a buffer transistor or a small relay. You will also need a small 12V power supply for the LED strip.

I will try and find an example on the web and post a link, unless someone else does so. How are your construction skills? Can you solder, or would you prefer to plug things into a breadboard?

Actually I just read your link. The LED strip is rated at 14.4W, which means 1.2A at 12V, which is a lot more than 300mA. No matter.

kermit911
Posts: 5
Joined: Mon Feb 24, 2014 9:21 pm

Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 2:18 am

I am very good with instructions, I can solder but plug and play is easier. I think the link I put up there is different then the LED's that I was looking at. When I was in the RadioShack store thats what the case said, 12V 300mA. I really appreciate all the effort you are putting in to help me, thank you very much. I build RC planes and robots so I am good with construction, and as long as there is a 1, 2, 3 I can put it together.

Thanks a lot!!!
Kermit

kermit911
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Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 2:58 am

I just bought a breadboard and a bunch of jumper wires.

Dave

ame
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Location: New Zealand

Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 3:13 am

Ok, well it's not so much a 1-2-3, more a case of following your nose and picking useful bits from other projects.

Here's the simplest example, using a single, regular LED:
https://projects.drogon.net/raspberry-p ... ingle-led/

But your project has a higher current and higher voltage.

Here's an example using a relay. The Pi can not drive a relay directly, it needs a buffer transistor. Depending on your relay you can control much bigger loads:
http://www.geekingabout.com/controlling ... -gpio.html

But, if you use a solid-state driver you can turn the LEDs on and off rapidly, which allows you to control their brightness:
http://mitchtech.net/raspberry-pi-pwm-rgb-led-strip/

In that example he is controlling three strips (red, green and blue) so he has three power transistors. You only need one as you are only driving one strip.

Oh, and you should find that most people here are helpful and happy to help, so ask any question.

Good luck.

4thdwarflord
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Location: Deep in the mines of Moria

Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 8:08 am

ame wrote:If that's all you need to do, then I'd recommend the "555". If you think you might want to do more then the Pi will do this and more. Or an Arduino. Take your pic.
Do i spy a pun?

ame
Posts: 3172
Joined: Sat Aug 18, 2012 1:21 am
Location: New Zealand

Re: Thinking about getting a Raspberry Pi

Tue Feb 25, 2014 8:34 am

4thdwarflord wrote:
ame wrote:If that's all you need to do, then I'd recommend the "555". If you think you might want to do more then the Pi will do this and more. Or an Arduino. Take your pic.
Do i spy a pun?
If the 555 wasn't a hint...

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